Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ANSC 462 - Monogastric Nutrition > 1.1 Comparative Digestive Anatomy > Flashcards

1.1 Comparative Digestive Anatomy Flashcards

1
Q

What is the definition of digestion? What does it involve?

A
  • Process that breaks feed down into simple substances that can be absorbed
  • Involves mechanical and chemical action of enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the definition of absorption?

A

Process of taking nutrients from the digested feed into the blood and lymph systems
- nutrients are absorbed into the blood stream, directly or indirectly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In monogastrics, where does most absorption occur?

A

Small intestine! Less amount in hindgut.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Oral cavity of a chicken vs a pig

A

Chicken
- birds use the beak (structure of keratin) to obtain bite-sized pieces of food
- the tongue is controlled by the hyoid apparatus (several bones) that has limited mobility; helps instead with obtaining and swallowing, but not with moving bolus around

Pig
- teeth, tongue, and salivary glands
- chewing action (mechanical part of digestion) wherein food is cut and torn, mixed with saliva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the salivary glands in birds well developed for?

A

Eating dry diets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Is amylase secretion important in the oral cavity of chickens?

A

Not active in oral cavity bc feed spends a limited amount of time there
- active in crop and proventriculus (if present)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Salivary glands of a pig

A
  • 3 paired sets
  • located under lower jaw and ear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is there little time for digestive activity in the oral cavity of chickens?

A

Residence time in oral cavity is minimal bc no chewing is taking place
- if enzymes are present, activity takes place in the crop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does digestive activity take place in the oral cavity of the pig?

A
  1. Saliva contains water, mucin, bicarbonate salts and enzymes
    - amylase and maltase
    - stimulates taste nerves
    - bicarbonate salts buffer pH in stomach
  2. Water moistens feed for chewing and swallowing
  3. Mucin lubricates feed for swallowing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Importance of feed taste?

A

Important for weaning piglets; taste is less important for chickens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the esophagus connect?

A

The oral cavity with the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Chicken esophagus

A

Larger diameter relative to mammals
- expandable (food being swallowed whole)
- mucus, immune & antimicrobial secretions

Many bird species have a crop = modification of the esophagus for storage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pig esophagus

A

Simple tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does a true crop have?

A

A controlling sphincter which regulates entrance and exit of food
- in the wild, the bird can forage for a large amount of food at once, then digest in safety

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the crop do?

A

Stores food (briefly) for anticipated need
- laying hens will increase calcium intake in anticipation of lights off (bc most of the egg shell is deposited at night)
- galliformes, hummingbirds, others; dusk feeding can supply a large proportion of energy needs during the night

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens if the gizzard is empty vs if it’s full?

A

Empty = food goes directly into gizzard

Full = food stored in crop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Beyond storage, what are 3 fxns of the crop?

A
  1. Secretion of mucus
    - lubrication of bolus
    - warm, moist enviro softens food
  2. Enzyme activity
    - little/no endogenous enzyme secretion, INSTEAD:
    - retrograde peristalsis
    - enzymes present in feed
    - microbial fermentation
  3. Immune fxn
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Because there is little/no endogenous enzyme secretion in the crop, where do enzymes come from to fulfill enzyme activity?

A
  1. Retrograde peristalsis
  2. Feed
  3. Microbial fermentation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Chicken stomach vs Pig stomach

A

Chicken: 2 organs
1. Proventriculus: glandular stomach (secretions)
2. Gizzard: muscular stomach (mixing)

Pig: 1 organ
- 4 distinct parts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is the proventriculus/gizzard affected by a whole wheat diet vs a ground wheat diet?

A

Whole wheat diet:
- better gizzard fxn = more muscular and a v big distinction btw proventriculus and gizzard

Ground wheat diet:
- flabby gizzard, no big distinction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Chicken proventriculus

A
  • glandular stomach
  • papillae on surface; gastric glands open at apex
  • HCl and pepsinogen secreted by gastric glands converted to pepsin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

4 regions of a pig stomach

A

*1 organ, many fxns

  1. Esophageal region
    - extension of esophagus
  2. Cardiac gland region
    - mucous cells: mucus, proteases, lipase
  3. Fundic (gastric gland) region
    - mucous cells
    - parietal cells: HCl
    - chief cells: proteases
  4. Pyloric gland region
    - mucous cells
    - chief cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Gastric juices are secreted by glands in the stomach and proventriculus walls, what does this do?

A

Contains HCl = drops pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How does starch digestion in the pig’s stomach differ from starch digestion in the chicken’s proventriculus/gizzard?

A

Not a lot of starch digestion takes place in the proventriculus/gizzard, unlike the pig where there is starch digestion taking place in the stomach.

  • Salivary amylases from oral cavity of pigs are still active to a certain extent in the stomach = continued starch digestion
  • Little starch digestion in birds; some attributed to retrograde peristalsis but those amylases are not suited for being active at the low pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does protein digestion start in the stomach/ proventriculus & gizzard?

A

Acidic enviro denatures protein = more points of attack for proteolytic enzymes

26
Q

Why is low pH important in the stomach/ proventriculus & gizzard?

A
  1. Protein digestion
    - conversion of inactive protease (pepsinogen) into more active protease (pepsin) for protein digestion
    - protein denaturation
  2. Chemical barrier for microbial passage into the SI
    - acidic enviro kills a lot of pathogenic bacteria
27
Q

What happens in the proventriculus?

A

Enzymes and acids are added

28
Q

Where is an important point of retrograde peristalsis in chickens?

A

Between the gizzard and proventriculus
- material goes through the pro to the giz where it is ground and mixed, then goes BACK to the pro where more enzymes etc. are added
- continual mixing; some material goes from giz to SI or from giz to pro (retrograde peristalsis)

29
Q

Chicken gizzard

A

Muscular stomach
- grinds food to reduce particle size and increase SA
- most peptic digestion occurs here
- larger/harder particle size = more important the gizzard; size and thickness of gizzard dependent on food type

30
Q

What is the size of the gizzard and thickness of muscle dependent on?

A

Food type

31
Q

Pig stomach

A

Stomach wall lined with muscle
- churns and squeezes the feed; particle size reduction fxn is achieved largely in the mouth
- gastric emptying forces liquid and feed into SI

32
Q

What is the cuticle (or koilin membrane) of the gizzard?

A

Covers the muscle of the gizzard and protects muscle from being degraded by proteolytic activity
- made up of protein and dead cells
- grinding, abrasive surface
- protects tissue from enzymes and acid
- thickness of cuticle dependent on type of diet

33
Q

What are “gizzard teeth”?

A

Dentate processes
- rods projecting from tubular glands to koilin surface
- act like sandpaper to grind feed

34
Q

What is the retention time of food in the gizzard dependent on?

A

*gizzard is the rate limiting step
- minutes to hours, depending on particle size
- ridges retain larger particles; smaller particles move along the bottom of the furrow

35
Q

What happens in the SI of both pigs and chickens?

A

Absorption of nutrients
- secretion of enzymes and hormones

36
Q

What are the 3 segments of the SI in both chickens and pigs?

A
  1. duodenum
  2. jejunum
  3. ileum
37
Q

What are the 3 arbitrary distinctions between segments of the chicken SI?

A
  1. Duodenum
    - first loop of SI, surrounds pancreas (attached)
  2. Jejunum
    - from duodenum to Meckel’s diverticulum
    - attached to residual yolk sac
    - attachment point of yolk during embryo development
  3. Ileum
    - from Meckel’s diverticulum to cecal jxn
38
Q

What are the 3 arbitrary distinctions between segments of the pig SI?

A

*based on relative length, not anatomical landmarks like the chicken

  1. Duodenum
    - 4-5%, first part
  2. Jejunum
    - 88-91%, middle part
  3. Ileum
    - 4-5%, last part
39
Q

What are 3 sources of secretions into the SI?

A
  1. Pancreas
    - enzymes, bicarbonate buffer
  2. Liver
    - bile acids/salts
  3. Intestinal walls
    - enzymes, mucus (rich in threonine, proline)
40
Q

Where does active digestion take place?

A

SI

41
Q

Where does most nutrient absorption occur in the SI?

A

Jejunum and ileum

42
Q

Enzyme activity in small intestine

A

Luminal = pancreatic enzymes

Mucosal = brush border enzymes

43
Q

Starch

A

starch = maltose = glucose

44
Q

Proteins

A

proteins = poly-, oligo-, di-peptides and AA = simple AA

45
Q

Fats

A

fats = fatty acids, glycerol and monoglycerides

46
Q

Musculature of the Si

A

Inner circular layer and outer longitudinal layer
- reverse peristalsis in birds leads to a more efficient digestive tract

47
Q

What do mammals have, that chickens do not in terms of the SI?

A

Central lacteals
- part of the lymphatic system in mammals that absorb fat from the SI
- in chickens, fat is absorbed into portal blood

48
Q

What are villi? What do they contain?

A
  • Small cone-shaped projections on the wall of the SI
  • Contain a network of blood capillaries through which nutrients enter the blood stream
49
Q

What are microvilli (brush border)? What are their 3 functions?

A

Tiny projections from the epithelial cells (enterocytes on the villus) of the intestine (especially SI)
- further increase SA
- digestive enzymes
- nutrient absorption

50
Q

The SI can broadly be described as being…

A

Multi-cellular and multi-functional

51
Q

Multi-cellular and multi-functional roles of the SI

A

Enterocytes
- nutrient assimilation

Goblet cells, lymphocytes, macrophages
- immune surveillance and host defense

Enteric neurons
- autonomous nervous system

Entero-endocrine cells
- major endocrine fxn

Microbes
- commensal microflora

52
Q

Why is there a high metabolic cost of a functional intestine?

A
  1. Cell turnover
  2. Nutrient absorption involves active transport
  3. Several dietary AA used as fuel
53
Q

What are 3 endogenous nutrients?

A

Enzymes, mucus, cells
- subject to digestion as dietary (exogenous) nutrients

54
Q

Chickens - endogenous nutrients

A
  • Endogenous nutrients high, but efficiently recovered
  • Retrograde movement allows secretions to be moved up intestine to site of absorption
  • Some absorption of microbial nutrients such as vitamins
55
Q

Pigs - endogenous nutrients

A
  • Unidirectional flow of digesta
  • Poorer recovery of endogenous nutrients
56
Q

What are the 2 main functions of the SI?

A
  1. Vasculature
    - supply nutrients to tissues
    - absorbed nutrients taken to liver
  2. Immune system (lymphocytes)
    - diffusely in lamina propria
    - aggregated in Peyer’s patches
    - more numerous in lower SI
57
Q

What are the 2 main functions of the hindgut?

A
  1. Microbial fermentation of undigested feed
    - Pigs and poultry need bacteria to degrade fiber
    - Main contribution of microbial fermentation to the overall nutrition of the animal are VFA
  2. Absorb water and electrolytes
58
Q

Chicken hindgut

A
  1. Colon (rectum)
    - intestine btw the ileocecal jxn and the cloaca
    - short, small in diameter
  2. Ceca
    - paired organs at the jxn of the small intestine and colon
    - ileocecal valves control entry of digesta
    - fermentation chambers —> VFA
    - water/nitrogen absorption
    - immunosurveillance (a lot of immune cells present)
  3. Cloaca
  4. Vent
59
Q

Pig hindgut

A
  1. Large intestine
    - Cecum: location for fermentation
    - Colon: largest part of the LI
    - Rectum
  2. Anus
    - external opening at the end of the DT
60
Q

What does the rectum in birds open into?

A

The cloaca

61
Q

Bird colon

A
  • rectum opens into the cloaca
  • larger diameter than the rectum; storage area for excreta
  • receives ureters and ducts of the reproductive tract
62
Q

Chickens excrete…

A

Excreta = feces + urine (primarily uric acid)

*feces are material that is not digested/absorbed

ANSC 462 - Monogastric Nutrition (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions